The paper shows the results of designing a high-quality electrically retunable resonator of 8-millimeter wave band. High quality of the reso- nator (unloaded Q is approximately 3000) is conditioned by the tact that electrical retuning of the frequency which is proportional to the elec- tromagnetic field charging in the range from 0 to 0.15 T is carried out by increasing the coupling of frequency-degenerated, high-quality wave- guide-dielectric resonances.